There exist various ways of seaming together netting panels forming trawl codends and in attaching such netting panels to riblines also forming the codend, including different tapers, such as point and bar taper, all point taper, cut ratios, tapering ratios, and the use of either square mesh, T0 mesh or T90 mesh. There are a plethora of factors involved in selecting how to design and configure a trawl codend, including whether or not to use riblines, and if riblines are used whether to form a two panel trawl codend that has two riblines, or whether to form a four panel trawl codend that has four riblines, how long to make the riblines relative to the stretch measure of the netting, what construction practices to employ in attaching one panel of netting to another and in attaching the netting to the riblines, and more. Furthermore, there exists no guarantee that a successful fashion of forming a codend for selectively fishing a particular fish species shall be successful for selectively fishing for another particular fish species.
With the current trend toward environmentally sound fishing practices in order to ensure sustainability of valuable fisheries for both fishermen as well as marine mammals and seabirds who depend upon fishery resources, increasingly precise gear designs having particular mesh arrangements in particular locations in the fishing net are required. Problematically, retaining the planned design parameters with current methods for attaching netting panels to frame lines is often so problematic and unreliable that it is not possible to deploy what might otherwise be a well functioning selective fishing net that releases undersized and juvenile fish as well as non-target species.
Thus, it readily can be appreciated that a long felt need exists in the industry for a frame line construction that more easily, more quickly, more simply, more reliably and more economically permits for attaching and, importantly, retaining in place for at least twelve months at a time, netting panels in particular locations relative to a frame line.
Known methods for attaching netting panels to frame lines, such as used in seines, bottom trawls, trawl codends for bottom and pelagic (i.e. “midwater”) trawls and backends and/or bellies for midwater trawls involve either directly lashing netting panels to a frame line or frame rope, or first forming yorkings (lacing loops) attached to the frame line, and then lashing netting panels directly to the yorking loops (lacing loops). The advantage of using yorkings (lacing loops) is that the ability of the netting panels to slide along the frame line is eliminated. Present methods for forming yorkings (lacing loops) onto frame lines involve passing a continues length of cord and/or rope through the lacing line in a generally traverse direction, pulling the entire continuous length of cord and/or rope through the frame line, knotting the continuous length of cord and/or rope about the frame line in the region of its passage through the frame line, subsequently passing the continuous length of rope through another portion of the frame line, and repeating the process. As the goal is to use a continuous length of loop, due to the fact that the material cost in cutting and retying cords and/or ropes to form each loop or yorking is prohibitively expensive, the man hours and time required to form known yorked frame lines (i.e. “lacing lines”) is rather high.
Due to the economic reality of the high cost of materials compared to the cost of labor, forming yorked frame lines with as much as possible a continuous length of rope and/or cord forming each loop and/or lacing loop in the yorked frame line (i.e. “lacing line”) is the present state of the art and current trend in the industry.
T90 is a name applied to conventional machine made netting when turned 90 degrees (90°) in relation to the direction usually used in making a trawl. The concept of ‘turned mesh’ or T90 netting is not new. The use of T90 netting has been investigated since the late 1980s. Testing has demonstrated that T90 netting when used in certain ways possesses some advantageous properties over machine made netting used in the conventional way, usually identified as T0 netting. For example, laboratory tests indicate that T90 netting is stronger than T0 netting. T90 netting technology has been developed for whole trawl application by the Icelandic trawl manufacturer Fjardanet that is part of the Hampidjan group. When used in the codend of a trawl, T90 netting exhibits better catch quality, better selectivity and more efficiency than codends with netting turned in the conventional direction. Experiences using T90 netting in the bellies and codends of groundfish trawls targeting cod found T90 netting filtered out large proportions of undersize cod and the nets had the added benefit of being easier to tow. However trawls and especially their brailer bags formed of T90 netting have acquired a reputation for rupturing under operating conditions in which a brailer bag made of T0 netting does not rupture. Furthermore, trawls or portions of trawls such as codends or brailer bags formed from T90 netting have acquired a reputation for causing excessive gilling of fish, especially in the backend or “belly” of trawls, the “tube” that is forward of a codend or brailer bag, as well as the codend or brailer bag itself.
With respect at least to pelagic trawls formed without riblines, and especially with respect to pelagic trawls whose codends are formed without riblines, and especially with respect to codends lacking hung-in riblines, the above stated problems associated with T90 netting have largely been addressed by teachings contained within published EP application EP2010015862 having Publication number EP2236025A1, and corresponding published U.S. application Ser. No. 12/798,287 with publication No. US 2010242336A1. This has led to markedly improved selectivity and fish escape of undersized, juvenile and non-target species where such fishing gear is in use, promoting sustainable fisheries where such fishing equipment is used.
Thus, it is the current state of the art and the present trend in the industry that codends formed with or mainly with T90 netting either lack riblines, have not more than two riblines.
However, with respect to trawl net codends that are formed with riblines, and especially when compared to trawl net codends with “hung-in” riblines, i.e. codends where the codends have riblines and where at least a particular portion of at least one of the codend's ribline's exhibits a lesser length compared to a length exhibited by a stretch measure length of a portion of netting including several meshes and attached to that particular portion of ribline, the teachings of EP2236025A1 have failed to provide for fishing gear that addresses the above stated problems. Due to above stated problems associated with T90 mesh codends that are formed with hung-in riblines, and mainly and particularly due to severe gilling problems that destroys the ability of the fishing gear to selectively fish, or to safely escape undersize, juvenile or non-target species, while also frustrating fishing of target species and target sized species fish, the use of T90 netting to form most or all of the netting in a riblined codend, and especially in a codend with hung-in riblines, has failed to be successful wherever it has been attempted, earned a negative reputation and has not been adopted by the industry.
As mentioned previously, despite being known for a long time that T90 netting exhibits advantageous properties, such as an the ability to increase water flow and to permit fish selectivity and enhanced fishery sustainability, which are long felt desires and needs in the industry, due to the above stated problems associated with the use of T90 netting in riblined condends, large costs associated with a faulty product such as a codend, and losses in operational revenues from repeated failures of T90 netting when used to mainly or exclusively from the netting of a riblined codend, T90 netting has failed to become widely used in the industry with codends having hung-in riblines, i.e. codends having riblines where the riblines are shorter in length than the stretch measure of a netting panel attached to a particular ribline (the stretch measure measured in a distance along the long dimension of the codend and in a straight line along the center of the netting panel) and has, in fact, earned a generally negative reputation.
However, riblined codends, and especially riblined codends that are hung-in, continue to be the only known codend construction that is economically viable for relatively large fisheries, and fisheries that have substantial environmental interaction with a variety of non-target species, and fisheries whose target species are found in blended concentrations of target and undersized fish.
For example, the current state of the art and the current trend in the industry in fishing for Atlantic Cod, Redfish, Haddock, Atlantic Pollock and bottom cod is to use a two (2) riblined codend forming a two (2) panel codend formed mainly or entirely from T0 netting, T90 netting having failed to be successful in such fisheries and application, and it is the current widely held belief in the industry that T90 netting is not economically or practically useful in such codends and fisheries. It is the trend in the industry that such codends use meshes formed of twines having diameters lesser than four point five millimeter (4.5 mm), it being the widely held belief in the industry that smaller twine diameters in codend mesh leads to improved escape and selectivity; use meshes having mesh sizes lesser than one hundred fifty millimeter (150 mm), it being the widely belief in the industry that mesh sizes larger than one hundred fifty millimeter (150 mm) lead to escape of all or the vast majority of target adult fish and thus are not economically useful or even practically possible to use; and that each panel of the codend have a horizontal stretch measure of at least 4800 mm (forty eight hundred millimeters). Presently, the largest mesh size used for such codends, i.e. riblined codends used for fishing Redfish, Atlantic Cod, Haddock, Atlantic Pollock and other cod, is with a mesh opening (i.e. “inside measurement”) of one hundred thirty-five millimeters (135 mm), equating to a mesh size (i.e. “full mesh”) value of lesser than one hundred fifty-five millimeters (155 mm), and the meshes forming such codends are entirely or mainly of T0 netting. It is the widely held belief in the industry that in order to maintain the same fishing selectivity for such codends but with T90 in substitution of T0 netting, that a mesh opening (i.e. “insider measurement”) of one hundred twenty millimeters (120 mm) is required, e.g. a T90 netting of one hundred thirty five millimeter (135 mm) mesh size (i.e. “full mesh”). While T90 mesh sizes up to equal to and lesser than one hundred sixty millimeters (160 mm) have been proposed in the teachings of EP2236025A1, such T90 mesh size teaching has failed to be adopted by the industry and it is the widely held belief in the industry that such mesh size is incapable of retaining target sized fish and thus is not practically useful.
As indicated above, it is the widely held belief in the industry that that a smaller mesh size must be used when transitioning from T0 netting to T90 netting due to the fact that T90 netting allows for more fish escape than does T0 netting. For this reason, for example, the industry believes that it is needed to use a 135 mm mesh size in T90 netting to replace a 155 mm mesh T0 netting in a codend. In fact, presently, none in the industry believe that it is possible to economically fish with a mesh size of greater than 135 mm for T90 netting on a codend using hung-in riblines, and it is the widely held belief in the industry that such a codend would escape all or nearly all fish, and in fact catch no or essentially no fish, making it economically impractical to use.
Problematically, such fisheries continue to catch and destroy a large amount of juvenile and undersized fish, as well as non-target species. Thus, it can readily be appreciated that a long felt need continues to exist in the industry for a more selective fishing codend construction for fishing Atlantic Cod, Redfish, Haddock, Atlantic Pollock and bottom cod.
Thus, it can readily be appreciated that due to the potential of T90 netting to selectively fish and permit safe escape of juvenile, undersized and non-target species, these practices being so important to sustainability of fisheries for the benefit of marine mammals, seabirds and humans, there exists a long felt need in the industry for a workable teaching that permits most or all of a riblined codend to be formed from T90 netting.
It is presently against the state of the art and contrary to the trend in the industry to form a codend for a trawl where both the codend has riblines that are hung-in and also where the mesh forming the codend is mainly or entirely formed of T90 mesh. It also is against the state of the art and contrary to the trend in the industry to form a riblined codend for a trawl having more than two riblines where the riblines are hung-in and also where the mesh forming the codend is mainly or entirely T90 mesh.